The present disclosure relates to containers, particularly to containers having one or two metal ends applied to one or both ends of the container body and crimp-seamed or double-seamed onto the container body, and most particularly to such containers used for retort processing and in which the container body is formed substantially of thermoplastic.
Traditionally, retort containers have been constructed substantially of metal. For many decades the standard retort food containers have been three-piece or two-piece metal cans. In a three-piece metal can, a metal can body is closed by a pair of metal ends that are typically double-seamed onto the ends of the can body. A two-piece metal can eliminates one of the metal ends because the can body is a deep-drawn body with an integral bottom wall. The metal ends of such typical retort containers have an outer peripheral portion forming a “curl” that receives the end of the can body, and after the end is applied the curl and the wall of the can body are rolled up together to form a double seam. This construction has the great advantage that it readily withstands retort processing without the seams being compromised, because the plastically deformed metal of the can body in the seam area tends to hold its deformed shape despite the high pressure and temperature during retort.
More recently there has been a desire to construct retort containers that use less metal, motivated by the potential cost reduction and improved aesthetics that such a construction can offer. The development described in the present disclosure at least in some aspects is aimed at addressing this desire.